The natural brooding instinct in hens - sitting on eggs to incubate them - has been largely eliminated in commercial laying breeds, with welfare implications for frustration of reproductive motivation in some production contexts.
The welfare of brooding behavior is context-dependent. In commercial production, genetic selection has largely eliminated the frustration of blocked brooding instinct by removing the instinct itself - though this represents a form of selective welfare management through behavioral engineering. Heritage breed hens in backyard systems who develop broodiness require management to either allow completion of the brooding cycle (with or without fertile eggs) or humane interruption. Chick-rearing, when permitted, allows expression of complex maternal behaviors including temperature regulation, predator protection, and social teaching that represent enriched welfare experiences. Backyard poultry keepers benefit from understanding brooding biology to manage welfare appropriately.